Seriamp is a Ruby library plus a collection of utilities and daemons to control a variety of receivers and amplifiers via serial connection (RS-232) or network (Ethernet/IP). The primary targets of Seriamp are Yamaha RS-232-capable receivers and Sonance Sonamp 875D SE/Mk2 amplifiers, as those are the models I primarily use, but some code is written for Yamaha YNCA protocol (usable over both RS-232C and Ethernet) and Onkyo/Integra/post-2014 Pioneer Elite receivers (which all use the Integra protocol). While not currently implemented, Seriamp should be straightforwardly extendable to support Denon and Marantz receivers, and perhaps with a bit more work the Harman/Kardon ones.

Seriamp features:

• Replaceable low level communication backends (for example, to support multiple serial port communication libraries in Ruby).
• A command-line tool and a web application for each supported device. The web application supports optional locking to prevent concurrent use of the device from multiple clients, which the hardware generally does not support.
• Command-line tools can route command execution through the respective web applications.
• Modular architecture that supports multiple protocols/device manufacturers.

The simplest use case of Seriamp is control of basic functionality of the supported hardware from a computer - for example, turning the hardware on and off, and adjusting volume.

The following are some uses of Seriamp that are either less obvious or that cannot be performed using other control methods (i.e. OEM remote control or front panel buttons/knobs) that I have employed in my home setup.

Yamaha for some reason likes to change the IR codes for the setup button and menu navigation buttons rather frequently, and does not place the equivalent buttons on the front panel of their receivers. This means that in order to configure their receivers from year 2000 onward, you generally must have the correct remote for that receiver. The higher tier receivers in particular can be difficult to get those correct remotes for, since there may be relatively few units manufactured that use a particular set of remote codes.

By sending the IR remote codes via Seriamp it is possible, theoretically, to configure all of these receivers without having the correct remote control.

I succeeded with controlling RX-V1500 in this way but RX-V1800 is ignoring the commands I've attempted so far.

The setup utility is yamaha-menu.

Yamaha receivers do not provide tone control buttons on their remotes, at least for the main zone. The protocol includes tone control remote IR codes for second and third zones (but, surprisingly, not for the main zone), therefore those should in theory be operable via the remote, but not the main zone. Normally the only way to adjust main zone tone controls is to walk to the receiver and operate the front panel knobs/buttons.

The extended RS232 protocol however provides commands to alter tone for the main zone, and can be used to implement remote tone control functionality.

Yamaha receivers provide commands for changing the speaker type (large/small), bass output (front main/subwoofer/both) and subwoofer crossover frequency. In a stereo system without a subwoofer, these commands can be combined to set up a high pass filter at a particular frequency (40-200 Hz). This is useful to omit the lowest frequencies at night.

Normally the receivers are not responding to control input when they are in standby (other than to the power button to turn themselves on). However both Yamaha and Integra receivers can alter their main zone volume while they are in standby. This permits having the volume clamped to a sensible range when the receiver is turned on.

Yamaha receivers permit setting Zone 2 and Zone 3 volumes in standby as well, whereas Integra (at least DTR-50.4) only permits the main zone volume to be set in standby.

The seriamp utility can control receivers and amplifiers from the command line. It can communicate directly to devices connected via the serial port to the computer on which it is invoked, devices connected via network and to both kinds via the seriamp-web daemon.

Assuming there is a Yamaha receiver attached via a USB to serial adapter to the local computer, the following command will interrogate this receiver for its status:

seriamp -m yamaha status

The syntax of seriamp command is:

seriamp -m module [options] command arg...

The module must be specified and it can be one of integra, sonamp, yamaha and ynca. See the documentation on the specific module about which hardware it supports.

Further options recognized are:

• -b, --backend BACKEND: specify the backend to use for communicating with the device. This is normally only needed for debugging.
• -d, --device DEVICE: specify the device address. For devices connected via a serial interface, this is the path to the device file, e.g. /dev/ttyUSB0. For devices connected via network (Ethernet or Wi-Fi), this is the IP address or the hostname of the device.
• -s, --service URL: communicate with the device via seriamp-web. This permits concurrent usage of one device by multiple clients, with seriamp-web providing the required locking. This can also speed up operations, especially over the serial protocol, because seriamp-web maintains a persistent connection to the device whereas seriamp must necessarily connect for each invocation.
• -t, --timeout TIMEOUT: the timeout to use for the operations. This timeout is applied to each operation performed by seriamp; for example, if seriamp is instructed to turn on two zones of a Sonamp amplifier, two commands are issued (one for each zone) and each command is allowed up to the specified timeout.

The command to issue can be specified on the command line as the following example shows:

seriamp -m yamaha status

Commands can also be given on standard input, with one command per line, in which case multiple commands can be issued with a single seriamp invocation which will reuse the connection to the receiver:

(echo 'volume -20'; echo status) |seriamp -m yamaha

Normally, only the output of the last command will be printed, but if --print-all option is given, the output of each command will be printed.

Each supported receiver/amplifier type comes with a command-line utility alias for the seriamp utility, named after the respective module. These are:

• integra
• sonamp
• yamaha (controls RS-232-capable Yamaha receivers via the serial port)
• ynca (controls network-capable Yamaha receivers via the YNCA protocol, serial or IP)

These utilities are a good starting point to explore the functionality available over the serial or network interfaces. By default, they issue commands directly to the receiver/amplifier (via either a serial port or network connection).

For "production" use, these utilities are also capable of routing the commands through the respective control daemons, described in the next section. This eliminates lost/broken responses that would happen when multiple clients are communicating with the same receiver/amplifier without mutual coordination.

Each supported receiver/amplifier type comes with a daemon that exposes the device's functionality over the network, permits safe access of the device by multiple clients, and provides state caching. The daemons are:

• integra-web
• sonamp-web
• yamaha-web

The daemons provide an HTTP API to control the respective device.

The "production" deployment of seriamp is to run one daemon on a computer closest to the receiver/amplifier being controlled and perform all operations on the receiver/amplifier by issuing commands to the daemon. The command-line utilities provide the --service command-line option to achieve this.

When Sonamp amplifiers are placed in RS-232 control mode, they lose the automatic power management for the zones which are serial controlled. This daemon performs the power management manually.

The daemon polls the power status of a receiver (currently, only Yamaha receivers are implemented) and turns the amplifier zones on or off to match the receiver power state.

When turning the zones on, the last state of the zones when the receiver was on prior to being turned off is used. For example, if initially the receiver is on and amplifier has zones 1 and 2 on and zones 3 and 4 off, the auto power daemon will make a note that zones 1 and 2 are on and zones 3 and 4 are off. If the receiver is turned off, the auto power daemon will turn off zones 1 and 2, retaining the knowledge that only those two zones had been on previously. If the receiver is then turn on, the auto power daemon will turn on amplifier zones 1 and 2 only.

Currently the auto power daemon requires the sonamp and the receiver webapp daemons to be running for accessing the respective devices - the auto power daemon does not implement direct access to either the receiver or the amplifier. This is because in practice all A/V equipment that is supported by Seriamp only works with a single control client (the webapp daemon in case of Seriamp), and direct access by multiple clients will produce errors and potentially erroneous behavior.

2-clause BSD.